Problème de code

Bonjour,
J'ai un problème avec se code quelqu'un pourrait m'aider
:





double a = 0 , z = 0 , e = 0 , r = 0 , t = 0 , y = 0 , u = 0 , i = 0 , o = 0 ;
double q = 0 , s = 0 , d = 0 , f = 0 ;
double total = a+z+e+r+t+y+u+i+o ;
int rep ;
Scanner sc = new Scanner (System.in) ;
do {

for ( int b = 1 ; b < 51 ; b++)
{

System.out.println("A: Cash");
System.out.println(" 1: 24 €");
System.out.println("Z: Bancontact");
System.out.println(" 2: 35,5 €");
System.out.println("E: Glyc");
if (q != 0) System.out.println(" 3: "+q+" €");
System.out.println("R: St-Jo");
if (s != 0) System.out.println(" 4: "+s+" €");
System.out.println("T: Vdv");
if (d != 0) System.out.println(" 5: "+d+" €");
System.out.println("Y: Mull");
if (f != 0) System.out.println(" 6: "+f+" €");
System.out.println("U: Mam");
if ( q != 0 && s != 0 && d != 0 && f != 0) System.out.println(" 0: ajoutez une valeur");
System.out.println("I: Chèq");
System.out.println(" -: 0 €");
System.out.println("O: Virement");
System.out.println("");
System.out.println("");
int w = 0 ;
do
{
System.out.println("requète:");
String str = sc.nextLine() ;
if ( str == "a1") a = a + 24 ;
if ( str == "z1") z = z + 24 ;
if ( str == "e1") e = e + 24 ;
if ( str == "r1") r = r + 24 ;
if ( str == "t1") t = t + 24 ;
if ( str == "y1") y = y + 24 ;
if ( str == "u1") u = u + 24 ;
if ( str == "i1") i = i + 24 ;
if ( str == "o1") o = o + 24 ;
if ( str == "a2") a = a + 35.5 ;
if ( str == "z2") z = z + 35.5 ;
if ( str == "e2") e = e + 35.5 ;
if ( str == "r2") r = r + 35.5 ;
if ( str == "t2") t = t + 35.5 ;
if ( str == "y2") y = y + 35.5 ;
if ( str == "u2") u = u + 35.5 ;
if ( str == "i2") i = i + 35.5 ;
if ( str == "o2") o = o + 35.5 ;
if ( q != 0 && str == "a3") a = a + q ;
if ( q != 0 && str == "z3") z = z + q ;
if ( q != 0 && str == "e3") e = e + q ;
if ( q != 0 && str == "r3") r = r + q ;
if ( q != 0 && str == "t3") t = t + q ;
if ( q != 0 && str == "y3") y = y + q ;
if ( q != 0 && str == "u3") u = u + q ;
if ( q != 0 && str == "i3") i = i + q ;
if ( q != 0 && str == "o3") o = o + q ;

if ( s != 0 && str == "a4") a = a + s ;
if ( s != 0 && str == "z4") z = z + s ;
if ( s != 0 && str == "e4") e = e + s ;
if ( s != 0 && str == "r4") r = r + s ;
if ( s != 0 && str == "t4") t = t + s ;
if ( s != 0 && str == "y4") y = y + s ;
if ( s != 0 && str == "u4") u = u + s ;
if ( s != 0 && str == "i4") i = i + s ;
if ( s != 0 && str == "o4") o = o + s ;

if ( d != 0 && str == "a5") a = a + d ;
if ( d != 0 && str == "z5") z = z + d ;
if ( d != 0 && str == "e5") e = e + d ;
if ( d != 0 && str == "r5") r = r + d ;
if ( d != 0 && str == "t5") t = t + d ;
if ( d != 0 && str == "y5") y = y + d ;
if ( d != 0 && str == "u5") u = u + d ;
if ( d != 0 && str == "i5") i = i + d ;
if ( d != 0 && str == "o5") o = o + d ;

if ( f != 0 && str == "a6") a = a + f ;
if ( f != 0 && str == "z6") z = z + f ;
if ( f != 0 && str == "e6") e = e + f ;
if ( f != 0 && str == "r6") r = r + f ;
if ( f != 0 && str == "t6") t = t + f ;
if ( f != 0 && str == "y6") y = y + f ;
if ( f != 0 && str == "u6") u = u + f ;
if ( f != 0 && str == "i6") i = i + f ;
if ( f != 0 && str == "o6") o = o + f ;

if (str == "0")
{
System.out.println("Nouvelle Valeur: ");
double nv = sc.nextDouble () ;
if ( q == 0) q = nv ;
if ( s == 0) s = nv ;
if ( d == 0) d = nv ;
if ( f == 0) f = nv ;
else System.out.println("Impossible d'encoder une nouvelle valeur!!!!! ( Il va faloir la réentrer à chaque fois :-( )");
int x = 0 ;
do{
System.out.println(" Dans quelle lieu ? :");
String str2 = sc.nextLine ();
char strChar = str2.charAt(0);
if ( strChar == a) a = a + 24 ;
if ( strChar == z) z = z + nv ;
if ( strChar == e) e = e + nv ;
if ( strChar == r) r = r + nv ;
if ( strChar == t) t = t + nv ;
if ( strChar == y) y = y + nv ;
if ( strChar == u) u = u + nv ;
if ( strChar == i) i = i + nv ;
if ( strChar == o) o = o + nv ;
else x = 1 ;
} while ( x == 1) ;


}

else w = 1
} while ( w == 1);

}
System.out.println("Cash = "+ a);
System.out.println("Bancontact = "+ z);
System.out.println("Glyc = "+ e);
System.out.println("St-Jo = "+ r);
System.out.println("Vdv = "+ t);
System.out.println("Mull = "+ y);
System.out.println("Mam = "+ u);
System.out.println("chèq = "+ i);
System.out.println("Virement = "+ o);
System.out.println("Total = "+ total);
System.out.println("");
System.out.println("");
do{
System.out.println("Voulez vous recommencez ?");
System.out.println("1: oui");
System.out.println("2: non");
System.out.println("réponse :");
rep = sc.nextInt () ;
} while ( rep != 1 && rep != 2);
} while ( rep == 1);